1. Field of the Invention
The present invention relates to a lubrication structure for a rolling bearing that is used for high speed rotation.
2. Description of the Related Art
By supplying lubrication oil to a rolling bearing, the rolling bearing is lubricated and cooled. A jet injection method and an inner ring lubrication method are known as a general method of lubricating the rolling bearing. FIGS. 1a and 1b show conventional lubrication structures of the rolling bearing. FIG. 1a shows the jet injection method, and FIG. 1b shows the inner ring lubrication method. In the drawings, the rolling bearing includes an inner ring 22a, an outer ring 22b, a plurality of rolling elements 22c installed between the inner ring 22a and the outer ring 22c, retainers 22d retaining the rolling elements 22c. 
In the jet injection method, lubrication oil 21 is injected from a jet nozzle 25 toward the side of the inner ring 22a of the bearing. In such a lubrication structure, as indicated by the arrows in FIG. 1a, after lubricating the bearing, the lubrication oil 21 passes through the bearing, and is accumulated in a bearing room. The lubrication oil 21 in the bearing room is scavenged to the outside by an oil scavenge pump (not shown in the drawing). However, in such a lubrication structure for the jet injection method, the lubrication oil 21 strikes a side surface of the retainers 22d of the bearing, and rebounds therefrom. In addition, the rebounding lubrication oil interferes with further supplying of the lubrication oil 21. Therefore, there is a problem in that the lubrication oil cannot be smoothly supplied to the inside of the bearing.
On the other hand, a lubrication structure for the inner ring lubrication method shown in FIG. 1b includes a lubrication oil hole 23 that radially penetrates through the inner ring 22a of the bearing, and an oil accumulating room 26 of which rotational axis is positioned on a rotational axis of the rolling bearing and that accumulates the lubrication oil 21 by using a centrifugal force of the rotation of the oil accumulating room 26. The lubrication structure of FIG. 1b further includes a lubrication oil supplying path 24 that communicates with the oil accumulating room 26 and the lubrication oil hole 23. Accompanying the rotation of the shaft 27, the lubrication oil 21 accumulated in the oil accumulating room 26 is rotated, and the centrifugal force of the rotated lubrication oil generates an oil supplying pressure. The generated oil supplying pressure causes the lubrication oil 21 to be supplied to the inside of the bearing via the lubrication oil supplying path 24 and the lubrication oil hole 23. According to this inner ring lubrication method, the lubrication oil can be supplied directly to the inside of the bearing, so that it is possible to more smoothly supply the lubrication oil than in the case of the lubrication structure for the above-mentioned jet injection method. A technique concerning such an inner ring lubrication method is disclosed in the following Patent Literature 1.
[Patent Literature 1]
Japanese Patent Official Publication No. 165178, 2001
However, even in the lubrication means using the above-mentioned inner ring lubrication method, there is a rotational speed difference between the oil accumulating room 26 and the lubrication oil 21, so that an adequate oil supplying pressure cannot be generated. For this reason, there is a problem in that there is a case where a sufficient quantity of lubrication oil actually used for the bearing lubrication cannot be obtained. Furthermore, since the rotational speed difference between the oil accumulating room and the lubrication oil is unknown, it is difficult to estimate a supplying quantity of lubrication oil. Therefore, there is a problem in that prediction of the lubrication oil quantity that is actually used for the bearing lubrication results in low accuracy.